National Aeronautics and Space Administration
Orbital Debris and Future Environment Remediation
J.-C. Liou, PhD NASA Orbital Debris Program Office Johnson Space Center, Houston, Texas
Presentations at the Korea Aerospace Research Institute (KARI) Daejon, Korea, 21-22 November 2011 National Aeronautics and Space Administration Outline
• Part 1 (Nov 21st): The Near-Earth Orbital Debris Environment – Overview of the orbital debris populations – Optical, radar, and in-situ measurements – Orbital debris modeling
• Part 2 (Nov 22nd): Environment Remediation and Active Debris Removal – Projected growth of the future debris population – The need for active debris removal (ADR) – Adhllfth21A grand challenge for the 21st century – The forward path
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Part 1: The Near-Earth Orbital Debris Environment
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Overview of the Orbital Debris Environment
4/72 JCL National Aeronautics and Space Administration The Near -Earth Environment (1957 -2010)
• Only objects in the US Space Surveillance Network (SSN) catalog are shown • Sizes of the dots are not to scale
5/72 JCL National Aeronautics and Space Administration What Is Orbital Debris?
• Orbital debris is any man-made object in orbit about the Earth that no longer serves a useful purpose
• Examples – Intacts: Spent rocket bodies (R/Bs, i.e., upper stages) and retired spp(acecraft (S/C, i.e., ppyayloads ) – Breakup fragments (via explosions or collisions) – Mission-related debris: objects released during normal mission operations ( engi ne covers, yo-yo didespinweihtights, etc.)
– Solid rocket motor effluents (Al2O3 slag and dust particles) – NaK droplets (coolant leaked from Russian nuclear reactors) – Surface degradation debris (paint flakes, etc.)
6/72 JCL National Aeronautics and Space Administration The Orbital Debris Family
Objects in the Near-Earth Environment
R/Bs, S/C
Breakuppg Fragments
Mission-related Debris l Debris NaK
Orbita Al2O3 Al2O3 (slag)
Paint Flakes MLI Pieces
MtMeteoroid s
10 μm 100 μm 1 mm 1 cm 10 cm 1 m 10 m
Size (diameter)
7/72 JCL National Aeronautics and Space Administration How Much Junk Is Currently Up There?
SfSoftball size or larger (≥10 cm): ~22,000 (tracked by the Space Surveillance Network)
Marble size or larger (≥1 cm): ~500,000
Dot or larger (≥1 mm): ~100, 000, 000 (a grain of salt)
• Total mass: ~6300 tons LEO-to-GEO (~2700 tons in LEO) • Debris as small as 0 .2 mm pose a realistic threat to Human Space Flight (EVA suit penetration, Shuttle window replacement)
8/72 JCL National Aeronautics and Space Administration The Environment
1.0E+6 LRIR flux, 350-600 km
1.0E+5 HAX Flux 450-600 km
1.0E+4 LDEF IDE, 300-400 km
SMM impacts 1.0E+3 LDEF craters (Humes) Larger Larger 1.0E+2 HST Impacts (Drolshagen), 500 km
1.0E+1 Space Flyer Unit, 480 km
Size and Size 1.0E+0 Goldstone radar, 300-600 km r] nn YY
- SMM holes
2 1.0E-1
SMM craters, 500-570 km 1.0E-2 LDEF craters (Horz) x of a Give of x mber/m 10E1.0E-3 uu Impact Kinetic Energy: EuReCa Impacts (Drolshagen), 500 km [Nu 1.0E-4 golf ball @ 10 km/sec ≈ 99165 TLEs, 450-600 km 1.0E-5 midsize sedan @ 120 mile/hr Mir (Mandeville, 2000) ctional Fl ee 1.0E-6
1.0E-7 Threat Regime Cross-s 1.0E-8 0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000 Diameter [cm] 9/72 JCL National Aeronautics and Space Administration An Example – Shuttle Vulnerabilities
Potential Shuttle Damage 6.5 Window Replacement
EVA Suit Penetration 5.5
Radiator Penetration
RCC Penetration
4.5 • Shuttle Loss of Crew andTPS Vehicl Tile Penetratione (LOCV) risks from MMOD impact
dithfdamage are in the range of 1Cabin in 250Penetrationto 1 in 300 per miiission
3.5 ¾ The risks vary with altitude, missionCargo duration, Bay Damage and attitude
¾ OD to MM is about 2:1 at ISS altitude
2.5
1.5
0.5 0.001 0.01 0.1 1 10 100 1000 Debris Diameter in Centimeters
10/72 JCL National Aeronautics and Space Administration Growth of the Historical Catalog Populations
Monthly Number of Objects in Earth Orbit by Object Type (SSN Catalog) 16000 15000 Total Objects 14000 Fragmentation Debris 13000 12000 Spacecraft
11000 Mission-related Debris 10000 Rocket Bodies s tt 9000 Iridium-Cosmos 8000 7000
r of Objec 6000 ~1000 are
ee FY-1C ASAT Test 5000 operational
Numb 4000 3000 2000 1000 0 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 55 55 66 66 66 66 66 77 77 77 77 77 88 88 88 88 88 99 99 99 99 99 00 00 00 00 00 11 11 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 20 20 20 20 20 20 Year 11/72 JCL National Aeronautics and Space Administration Sources of the Catalog Populations
• ~4700 launches conducted worldwide since 1957 • 208 known breakups – Major events: • Titan Transtage (473, 1965) Source Breakdown • Agena D stage (373, 1970) anom. debris, • Ariane 1 stagg(e (489, 1986) 1.9% • Pegasus HAPS (709, 1996) payloads, • Long March 4 stage (316, 2000) 25.2% • PSLV (326 , 2001)
• Fengyun 1C (~3200, 2007) breakup • Briz-M (>1000a, 2007) debris, 47.7% rocket bodies, • Cosmos 2421 (509, 2008) 12.9% • Iridium 33 (>700, 2009) mission‐ • Cosmos 2251 (>1500, 2009) related dbidebris, 12.3% 3% ainitial report
12/72 JCL National Aeronautics and Space Administration Accidental On-Orbit Collisions
• Four accidental collisions between cataloged objects have been identified – 1991: Russian Sat (launched in 1988) ↔ Russian fragment – 1996: French Sat (launched in 1995) ↔ French fragment – 2005: US R/B (launched in 1974) ↔ PRC fragment – 2009: Iridium 33 (launched in 1997) ↔ Cosmos 2251 (launched in 1993)
Iridium33 Cosmos 2251 (560 kg) (900 kg ) CERISE (1996)
13/72 JCL National Aeronautics and Space Administration
Optical, Radar, and In-Situ Measurements
14/72 JCL National Aeronautics and Space Administration Current NASA Debris Data (1/2)
36,000 MODEST telescope
10,000 Goldstone radars (>32. 2º) Haystack radar (>30º)
2000
1000
HST-WFPC2 (580x610 km, 93-09) U.S. Space Surveillance Network STS (300x400 km, 95-11)
HAX radar (>42.6º) 100
10 μm 100 μm 1mm1 mm 1cm1 cm 10 cm 1m1 m 10 m (*Boundaries are notional.) Particle Diameter
15/72 JCL National Aeronautics and Space Administration Current NASA Debris Data (2/2)
Goldstone radars 36,000Haystack (30-m dish, X-band) MODEST telescope HAX (12.2-m dish, 10,000 Ku-band) Goldstone radars (>32. 2º) Haystack radar (>30º)
2000 DSS-14 (70-m dish, X-band) DSS-15 (34-m dish receiver) 1000
HST-WFPC2MODEST (580x610 (0.6-m, km, Cerro 93-09) Tololo) U.S. Space Surveillance Network STS (300x400 km, 95-11)
HAX radar (>42.6º) 100 Impact crater
10 μm 100 μm 1mm1 mm 1cm1 cmHST WFPC10- 2radiator2 cm radiator 1m1 m 10 m (*Boundaries are notional.) Particle Diameter
16/72 JCL National Aeronautics and Space Administration NASA RADAR Observations
• Signal processing • Object detection/correlation • Debris size estimation • Orbit determination • Environment definition Goldstone
Haystack and HAX
17/72 JCL National Aeronautics and Space Administration NASA Optical Observations
• Photometric and spectral measurements • Object detection and correlation • Optical Measurement Center (OMC) • SfSurface mat tilidtifitierial identification • Orbit determination • Environment definition MODEST
MCAT
OMC 18/72 JCL National Aeronautics and Space Administration In-Situ Data from Returned Surfaces
WFPC2
radiator
19/72 JCL National Aeronautics and Space Administration Inspection of the HST WFPC2 Radiator
• 685 impact features (≥300 µm) were identified – Recorded each impact feature’s shape, size, depth, and volume
1 mm 300 µm
20/72 JCL National Aeronautics and Space Administration Critical Data Gaps
36,000 MODEST Gap 2 telescope 10,000 Goldstone radars (>32. 2º) Haystack radar (>30º)
2000
1000
HST-WFPC2 (580x610 km, 93-09) U.S. Space Gap 1 Surveillance Network STS (300x400 km, 95-11)
HAX radar (>42.6º) 100
10 μm 100 μm 1mm1 mm 1cm1 cm 10 cm 1m1 m 10 m (*Boundaries are notional.) Particle Diameter
21/72 JCL National Aeronautics and Space Administration Future NASA Debris Telescope
• NASA Meter Class Autonomous Telescope (MCAT) – 1.3 m aperture, 0.96° field of view, f/4 – Located at Kwajalein Atoll (9°N, 168°E) – Target detection limits • GEO ~10 cm diameter (20.5 V-mag) – Primary objectives • GEO debris down to ~10 cm • LEO debris with low inclinations and high eccentricities • Simu ltaneous rad ar-optical ob servati ons – Expected operations ~2012
22/72 JCL National Aeronautics and Space Administration A New Particle Impact Detection Technology
• Debris Resistive/Acoustic Grid Orbital Navy Sensor (DRAGONS) – Objective: A low-cost/mass/power experiment to detect and characterize 0. 1 to 1 mm MMOD particles at 800-1000 km altitude – Components: (1) a large surface (≥1 m2) coated with thin resistive grids, (2) acoustic sensors attached to the backside of the board/film – Team: USNA , NASA/ODPO , Ken t (UK), NRL, VT – Status: Presented to the annual DoD Space Experiment Review Board (SERB) since 2007, no firm flight opportunity identified by STP
Hypervelocity Impact Tests • Resistive grid width: 75 μm •Projectile: 0.3 mm stainless steel • Impact speed: 5.06 km/sec • Impact angle: normal • Two PVDF acoustic sensors attached to the board
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Modeling
24/72 JCL National Aeronautics and Space Administration General Orbital Debris Modeling (1/2)
• Evolutionary model – Is a physical model (such as LEGEND) capable of predicting future debris environment – StthdltSupports the development ofUS/NASAdf US/NASA de bibris mitiga tion guidelines and safety standards • Engineering model – Is a mathematical model (such as ORDEM) capable of predicting OD impact risks for the International Space Station and other critical space assets • Satellite breakup model – Descr ibes the ou tcome o f a sa tellit e brea kup (exp los ion or collision)
25/72 JCL National Aeronautics and Space Administration General Orbital Debris Modeling (2/2)
• Reentry risk assessments – Uses Object Reentry Survival Analysis Tool (ORSAT) to evaluate satellite reentry risks – ThikfhThe risk of human casua ltflty from surv iidbihlltiving debris shall not exceed 1 in 10,000 (NASA Standard 8719.14)
Delta II propellant tank Titanium casting of STAR-48B SRM Titanium casting of STAR-48B SRM (Georgetown, TX, 1997) (Saudi Arabia, 2001) (Argentina, 2004)
26/72 JCL National Aeronautics and Space Administration LEGEND
• LEGEND, A LEO-to-GEO Environment Debris model – Is a high fidelity, three-dimensional numerical simulation model for long-term orbital debris evolutionary studies – IldIncludes itintac ts (rock et b odi es an d spacecra ft), m iss ion-reltdlated debris (rings, caps, etc), and explosion/collision fragments – Uses a deterministic approach to mimic the historical debris environment based on recorded launches and breakups – Uses a Monte Carlo approach and an innovative, pair-wise collision probability evaluation algorithm to simulate future collision activities – Projects future environment based on user-specified launch traffics, postmission disposal and active debris removal options – Nine peer-reviewed journal papers have been published about LEGEND and its applications since 2004
27/72 JCL National Aeronautics and Space Administration ORDEM
• ORDEM, An Orbital Debris Engineering Model – Is a mathematical model for orbital debris impact risk assessments for the International Space Station and other critical space assets – Describes the orbital debris environment in terms of spatial density, impact velocity distribution, impact flux, etc – Is based on recent empirical radar, optical, and in-situ measurement data – The current model , ORDEM2000 , is available for download at http://www.orbitaldebris.jsc.nasa.gov/model/engrmodel.html – An upp,,dated version, ORDEM 3.0, will be released in the coming months • Extends the coverage to GEO • Includes uncertainty estimates
28/72 JCL National Aeronautics and Space Administration Satellite Breakup Model
• The NASA Standard Breakup Model – Describes the outcome of a typical satellite explosion or collision • Size, area -to-mass ratio, and ΔV distributions of the fragments – Is a key element for short- and long-term debris modeling – Is based on observations of on-orbit breakup events and laboratory experiments – Has been adopted by major international space agencies for their debris evolutionary models – A new ground-based satellite impact experiment is underway
29/72 JCL National Aeronautics and Space Administration DAS
• DAS, the NASA Debris Assessment Software – Is designed to assist NASA Programs in performing orbital debris assessments for their planned missions • Assessment requirements are described in NASA -STD-8719. 14 “Process for Limiting Orbital Debris” • DAS 2.0 addresses requirements point-by-point ¾ Limit number and orbital lifetime of debris passing through LEO , limit liftime of objects passing near GEO, limit probability of accidental explosion during mission operations, etc. – Includes orbit propagg(ators (for LEO, GTO, and GEO ), debris environment model, and a simplified version of NASA’s Object Reentry Survival Analysis Tool (ORSAT) for reentry- survivability assessments – Is available for download at http://www.orbitaldebris.jsc.nasa.gov/mitigate/das.html
30/72 JCL National Aeronautics and Space Administration ORSAT
• ORSAT, NASA’s Object Reentry Survival Analysis Tool – Is designed to provide a high fidelity assessment of space vehicl e and component reent ry survi vabilit y • Per U.S. Government Orbital Debris Mitigation Standard Practices, the threshold of human casualty risk from reentering debris shall not excee d 1 i n 10 , 000 per reen try even t – Includes trajectory, atmosphere, aerodynamics, aerothermodynamics, thermal / ablation, and debris casualty area analyses – Outputs component demise altitude or location, surviving mass, kinetic energy of impact , and human casualty risk
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QtifPtI?Questions for Part I?
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Pt2NPart 2: Near-EthEiEarth Environment Remediation and Active Debris Removal
33/72 JCL National Aeronautics and Space Administration Growth of the Historical Catalog Populations
Monthly Number of Objects in Earth Orbit by Object Type (SSN Catalog) 16000 15000 Total Objects 14000 Fragmentation Debris 13000 12000 Spacecraft
11000 Mission-related Debris 10000 Rocket Bodies s tt 9000 Iridium-Cosmos 8000 7000
r of Objec 6000 ~1000 are
ee FY-1C ASAT Test 5000 operational
Numb 4000 3000 2000 1000 0 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 55 55 66 66 66 66 66 77 77 77 77 77 88 88 88 88 88 99 99 99 99 99 00 00 00 00 00 11 11 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 20 20 20 20 20 20 Year 34/72 JCL National Aeronautics and Space Administration Mass in Orbit
Monthly Mass of Objects in Earth Orbit by Object Type 6.5
6.0
5.5 LEO to GEO: ~6300 tons 5.0 LEO only: ~2700 tons Total 4.5
4.0 ns of ns of kg) oo 3.5 Spacecraft 3.0 There is no sign of slowing down! rbit (milli 2.5 OO 2.0 Rocket Bodies 1.5 Mass in 101.0 Mission-related Debris
0.5 Fragmentation Debris 0.0 6 8 0 2 44 6 8 0 2 44 6 8 0 2 44 6 8 0 2 44 6 8 0 2 44 6 8 0 2 195 195 196 196 196 196 196 197 197 197 197 197 198 198 198 198 198 199 199 199 199 199 200 200 200 200 200 201 201 Year 35/72 JCL National Aeronautics and Space Administration Sources of the Catalog Population – All
Number Breakdown Mass Breakdown
others, 9.7%
others, France, 18.9% CIS, 5.3% China, 37.8% CIS, 21.7% 48.3%
USA, USA, 27.6% 30.8% LEO‐to‐GEO LEO‐to‐GEO CIS = Former Soviet Republics
36/72 JCL National Aeronautics and Space Administration Sources of the Catalog Population – LEO Only
Number Breakdown Mass Breakdown
others, others, 4.8% 10.0% China, 4.2%
China, CIS, 27.7% 39.0% USA, 23.4% CIS, 62.4% USA, 28.4% LEO only LEO only CIS = Former Soviet Republics
37/72 JCL National Aeronautics and Space Administration Spatial Density of the Catalog Population (1/2)
LEO to GEO 1.E‐07
1.E‐08 ) 3 1.E‐09 (no/km
1.E‐10 tial Density aa
Sp 1.E‐11
LEO
1E1.E‐12
GEO
1.E‐13 0 10000 20000 30000 40000 Altitude (km)
38/72 JCL National Aeronautics and Space Administration Spatial Density of the Catalog Population (2/2)
LEO 6.E‐08
5.E‐08 ) 3 4.E‐08 (no/km
3.E‐08 tial Density aa FY-1C
Sp 2.E‐08 ASAT test
1E1.E‐08 Iridium 33 / Cosmos 2251 collision 0.E+00 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 Altitude (km)
39/72 JCL National Aeronautics and Space Administration Mass Distribution in LEO
Mass Distribution in LEO 350
300 All Bin Rocket Bodies (46% of All) 250 Spacecraft (51% of All) Others
kmAltitude 200 00
150 c ton) c ton) per 5
100 Mass (metri 50
0 200 400 600 800 1000 1200 1400 1600 1800 2000 Altitude (km) ISS (~400 tons) not included 40/72 JCL National Aeronautics and Space Administration
Projected Growth of the Future Debris Environment
((,,Worst case, best case, and “realistic” scenarios)
41/72 JCL National Aeronautics and Space Administration Debris Environment Modeling
• All environment simulations are based on LEGEND (an LEO-to-GEO Environment Debris model) – LEGEND is the higgyh fidelity orbital debris evolutionar y model developed by the NASA Orbital Debris Program Office
– LEGEND simulates objjypjects individually, incorporates major perturbations in orbit propagation, and includes major source and sink mechanisms (launches, breakups, decays)
– Ten peer-reviewed journal papers have been published on LEGEND and its applications since 2004
– The following discussions will focus on ≥10 cm objects and limit the future projection to 200 years
42/72 JCL National Aeronautics and Space Administration Peer-Reviewed Journal Publications (LEGEND and LEGEND Applications)
1. Liou, J.-C. et al., LEGEND – A three-dimensional LEO-to-GEO debris evolutionary model. Adv. Space Res. 34, 5, 981-986, 2004. 2. Liou, J.-C. and Johnson, N.L., A LEO satellite postmission disposal study using LEGEND, Acta Astronautica 57, 324-329, 2005. 3. Liou, J.-C., Collision activities in the future orbital debris environment, Adv. Space Res. 38, 9, 2102-2106, 2006. 4. Liou, J.-C. and Johnson, N.L., Risks in space from orbiting debris, Science 311, 340-341, 2006. 5. Liou, J .-C., A statistic analysis of the future debris environment, Acta Astronautica 62, 264-271, 2008. 6. Liou, J.-C. and Johnson, N.L., Instability of the present LEO satellite population, Adv. Space Res. 41, 1046-1053, 2008. 7. Liou, J .-CdJhC. and Johnson, N NLChtitifthtldF.L., Characterization of the cataloged Fengyun-1C fragments and their long-term effect on the LEO environment, Adv. Space Res. 43, 1407-1415, 2009. 8. Liou, J.-C. and Johnson, N.L., A sensitivityyy study of the effectiveness of active debris removal in LEO, Acta Astronautica 64, 236-243, 2009. 9. Liou, J.-C. et al., Controlling the growth of future LEO debris populations with active debris removal, Acta Astronautica 66, 648-653, 2010. 10. Liou, J .-C., An active debris removal parametric study for LEO environment remediation, Adv. Space Res. 47, 1865-1876, 2011.
43/72 JCL National Aeronautics and Space Administration Future Projection – The Worst Case Scenario (Regular Satellite Launches, but No Mitigation Measures) Non-Mitigation Projection (averages and 1-σ from 100 MC runs) 70000
LEO (200-2000 km alt)
60000 MEO (2000-35,586 km alt) 10 cm)
>> GEO (35 , 586-35,986 km alt) 50000 Objects ( Objects ff 40000
30000 Number o Number ee
20000 Effectiv
10000
0 1950 1970 1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 Year (Liou, 2010) 44/72 JCL National Aeronautics and Space Administration Assessments of the Non-Mitigation Projection
• LEO: the non-mitigation scenario predicts the debris population (≥10 cm objects) will have a rapid non-linear increase in the next 200 years – This is a well-known trend (the “Kessler Syndrome”) that was the motivation for developing the currently-adopted mitigation measures (e.g., the 25-yy)r rule) in the last 15 years
• MEO and GEO: the non-mitigation scenario predicts a moderate population growth – Only a few accidental collisions between ≥10 cm objects are ppyredicted in the next 200 years – The currently-adopted mitigation measures (including EOL maneuvers in GEO) will further limit the population growth – Environment remediation is not urgent in MEO and GEO
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Will the Commonly-Adopted Mitigation* Measures Stabilize the Future LEO Environment?
*Mitigation = Limit the generation of new/long-lived debris (NPR 8715.6A, NASA-STD-8719. 14, USG OD Mitigation Standard Practices , UN Debris Mitigation Guidelines, etc.)
46/72 JCL National Aeronautics and Space Administration Future Projection – The Best Case Scenario (No New Launches Beyond 1/1/2006)
12000 Total ItIntact s + mi ssi on rel ltddbiated debris 10000 Explosion fragments Collision fragments
10cm, LEO) 10cm, 8000 >>
6000 of Objects of ( rr
4000 tive Numbe cc 2000 Effe
0 1950 1970 1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 Year (Liou and Johnson, Science, 2006) • Collision fragments replace other decaying debris through the next 50 years, keeping the total population approximately constant • Beyond 2055, the rate of decaying debris decreases, leading to a net increase in the overall satellite population due to collisions
47/72 JCL National Aeronautics and Space Administration Assessments of the No -New-Launches Scenario
• In reality, the situation will be worse than the “no new launches” scenario as – Satellites launches will continue – Major unexpected breakups may continue to occur (e.g., Fengyun-1C)
• Postmission disposal (such as a 25-year decay rule) will help, but will be insufficient to prevent the self- generating ph enomenon f rom h appeni ng
• To preserve the near-Earth space for future generations, ADR must be considered
48/72 JCL National Aeronautics and Space Administration Conclusions of the 2006 Paper
• “The current debris population in the LEO region has reached the point where the environment is unstable and collisions will become the most dominant debris- generating mechanism in the future .”
• “Only remediation of the near-Earth environment – the removal of exi sti ng l arge obj ect s f rom orbit – can prevent future problems for research in and commercialization of space.”
- Liou and Johnson, Science, 20 January 2006
49/72 JCL National Aeronautics and Space Administration Environment Projection With Mitigation Measures
Average Collisions in the Next 200 Years
i-i collisions i-f collisions f-f collisions total cat /non-cat cat /non-cat cat /non-cat cat /non-cat
10 / 0 11 / 21 3 / 2 24 / 23
50/72 JCL National Aeronautics and Space Administration International Consensus
• The LEO environment instability issue is under investigation by the Inter-Agency Space Debris Coordination Committee (IADC) members • An official “Stability of the Future LEO Environment” comppyarison study, was initiated in 2009 – Six participating members: NASA (lead), ASI, ESA, ISRO, JAXA, and UKSA – Resu lts from the si x diff eren t mo de ls are cons is ten t w ith one another, i.e., even with a good implementation of the commonly- adopted mitigation measures, the LEO debris population is expected to increase in the next 200 years – Study summary was presented at the April 2011 IADC meeting
51/72 JCL National Aeronautics and Space Administration
Preserving the Environment with Active Debris Removal (ADR* )
*ADR = Removing debris beyond guidelines of current mitigation measures
52/72 JCL National Aeronautics and Space Administration Key Questions for ADR
• Where is the most critical region for ADR?
• What are the mission objectives?
• What objects should be removed first? – The debris environment is very dynamic. Breakups of large intacts generate small debris, small debris decay over time,…
• What are the benefits to the environment?
• How to do it? → The answers will drive the top-level requirements, the necessary technology development, and the implementation of ADR operations
53/72 JCL National Aeronautics and Space Administration How to Define Mission Success?
• Mission objectives guide the removal target selection criteria and the execution of ADR • Common objectives – Follow practical/mission constraints (in altitude, inclination, class, size, etc.) – Maximize benefit-to-cost ratio • Specific objectives – Control population growth (small & large debris) Target large & – Limit collision activities massive intacts – Mitigate mission-endingg( risks (not necessaril y Target catastrophic destruction) to operational payloads small debris – Mitigate risks to human space activities – And so on
54/72 JCL National Aeronautics and Space Administration
Target Small Debris
55/72 JCL National Aeronautics and Space Administration One Example: Risks From Small Debris
• The U.S. segments of the ISS are protected against orbital debris about 1.4 cm and smaller – “Currently,” the number of objects between 1.5 cm and 10 cm, with or bits cross ing tha t o f the ISS, is approx ima te ly 1200 • ~800 of them are between 1.5 cm and 3 cm – To reduce 50% of the ISS-crossing orbital debris in this size range (1.5 cm to 3 cm) will require, for example, a debris collector/remover with an area-time product of ~1000 km2 year
56/72 JCL National Aeronautics and Space Administration Small Debris Environment Is Highly Dynamic
Evolution of Cosmos 2251 Fragments (5 mm to 1 cm) 50,000
45,000 2009 (~163,000)
40,000 2011 (~100,000)
2013 (~87,000) Bin
35,000 − At any given altitude below ~900 km, small debris continue km
2015 (~67,000) 50 30,000 to spp,iral toward lower altitude, and the same region rr 2017 (~59,000) pe continues to be replenished by debris spiraling down from 25,000 higher 2019altitude (~43,000) Objects − The small debris environment is highly dynamic and could
of 20,000 have strong short-term (i.e., monthly to yearly) episodic 15,000 variations Number
10,000
5,000
0 400 500 600 700 800 900 1000 1100 1200 Altitude (km)
57/72 JCL National Aeronautics and Space Administration
Target Large Debris
58/72 JCL National Aeronautics and Space Administration Targeting the Root Cause of the Problem
• A 2008-2009 NASA study shows that the two key elements to stabilize the future LEO environment (in the next 200 years) are – A good implementation of the commonly-adopted mitigation measures (passivation, 25-year rule, avoid intentional destruction,,) etc.)
– An active debris removal of about five objects per year
• These are objects with the highest [ M × Pcoll ] • Many (but not all) of the potential targets in the current environment are spent Russian SL upper stages ¾ Masses: 14t1.4 to 8 89t.9 tons ¾ Dimensions: 2 to 4 m in diameter, 6 to 12 m in length ¾ Altitudes: ~600 to ~1000 km regions ¾ Inclinations: ~7 well-defined bands
59/72 JCL National Aeronautics and Space Administration Controlling Debris Growth with ADR
LEO Environment Projection (averages of 100 LEGEND MC runs) 24000
22000 Reg Launches + 90% PMD
20000 Reg Launches + 90% PMD + ADR2020/02 Reg LLhaunches + 90% PMD + ADR2020/05 18000 cm)
16000 (>10
cts
ee 14000 Obj
of
12000
10000 umber NN
A good implementation of the commonly -adopted 8000 mitigation measures and an ADR of ~5 objects per
6000 year can “stabilize the future environment” Effective
4000
2000
0 1950 1970 1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 Year (Liou, Adv. Space Res, 2011) 60/72 JCL National Aeronautics and Space Administration Projected Collision Activities in LEO
50
Reg Launches + 90% PMD LEO) 40 Reg Launches + 90% PMD + ADR2020/02 cts,
ee Reg Launches + 90% PMD + ADR2020/05 obj
cm
30 >10 ((
Collisions
20 f oo
A good implementation of the commonly-adopted Number
e 10
vv mitiggjpation measures and an ADR of ~5 objects per year can only reduce the collisions by ~50% Cumulati 0 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 Year (Liou, Adv. Space Res, 2011)
61/72 JCL National Aeronautics and Space Administration Potential Active Debris Removal Targets
Top 500 Current R/Bs and S/Cs 1600 SL-8 2nd stage
1500
1400 Apogee
Perigee 1300 SL-16 R/B (8900 kg) Active DebrisCosmos Removal (3300 kg) – A Grand Engineering 1200
) Envisat Challengemm forSL-8 the R/B (1400 Twenty kg) -First Century
(k 1100
1000 SL-8 R/B (1400 kg)
CosmosAltitude (1300 kg) METEOR (2000 kg) 900
SL-3 R/B (1440 kg) 800 METEOR (2200-2800 kg) Various R/Bs and S/Cs 700 (SL-16 R/B, Envisat, etc., SL-8 R/B (1400 kg) 1000-8900 kg) 600 Cosmos (2000 kg) Cosmos (2500 kg)
500 60 65 70 75 80 85 90 95 100 105 Inclination (deg) (Liou, Adv. Space Res, 2011) 62/72 JCL National Aeronautics and Space Administration National Space Policy of the United States of America (28 June 2010) • Orbital debris is mentioned on 4 different ppgages for a total of 10 times in this 14-page policy document • On page 7:
Preserving the Space Environment and the Responsible Use of Space
Preserve the Space Environment. For the purposes of minimizing debris and preserving the space environment for the responsible, peaceful, and safe use of all users, the United States shall: • … • Pursue research and development of technologies and techniques, througgph the Administrator of the National Aeronautics and Space Administration (NASA) and the Secretary of Defense, to mitigate and remove on-orbit debris, reduce hazards, and increase understanding of the current and future debris environment; and • …
63/72 JCL National Aeronautics and Space Administration Challenges for ADR Operations
Operations Technology Challenges
Single-object removal per launch is not feasible from Launch cost perspective
Solid, liquid, tether, plasma, laser, drag-enhancement Propulsion devices, others? Precision Tracking Ground or space-based
GN&C and Rendezvous Autonomous, non-cooperative targets
Stabilization (of the tumbling targets) Physical or non-physical, how
Physical (where, how) or non-physical (how), Capture or Attachment do no harm
Deorbit or Graveyard Orbit When, where, reentry ground risks • Other requirements: – Affordable cost – Repea ta bility o f the remova l sys tem (in space ) – Target R/Bs first
64/72 JCL National Aeronautics and Space Administration The First Step
• Identify top-level requirements for an end-to-end ADR operation – Launch, propulsion, precision tracking, GN&C, rendezvous, stabilization, capture/attachment, and deorbit/graveyard maneuvers – Define stakeholders and their expectations to drive the development of a concept of operations • CdtiiConduct mission d diesign anal yses and est tblihablish a feasible forward plan – Identify TRLs of existing technologies – Evaluate pros and cons of different technologies (e.g., space tug vs. drag-enhancement devices) – Iden tify t ech nol ogy gaps ( e.g., ways to st abili ze a mass ive, non-cooperative, fast spinning/tumbling target) – Perform trade studies (e.g., physical vs. non-physical capture; deorbit vs. graveyard orbit)
65/72 JCL National Aeronautics and Space Administration An Example – Deorbit With Drag-Enhancement Devices
Orbital Lifetime of a Typical SL‐8 2nd Stage (950 km, 83°) 7500
>200 years
7300 11 years 25 years
Actual A/M (0.015 m2/kg) (km) 7100 Enhanced A/M, 004.4 m2/kg → ~30 m balloon 2 years Axis → ~50 m balloon Enhanced A/M, 1.4 m2/kg Enhanced A/M, 5.5 m2/kg → ~100 m balloon
imajor 6900 mm Se
6700
6500 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060 Year 66/72 JCL National Aeronautics and Space Administration
Summary
67/72 JCL National Aeronautics and Space Administration Concluding Remarks (1/4)
• The LEO debris population will continue to increase even with a good implementation of the commonly- adopted mitigation measures – The increase is driven by catastrophic collisions involving large and massive intacts – The major mission -ending risks for most operational satellites, however, comes from impacts with debris just above the threshold of the protection shields (~5 mm to 1 cm)
68/72 JCL National Aeronautics and Space Administration Concluding Remarks (2/4)
Notional Size Distribution of LEO‐Crossing Objects 10,000,000
~80% of all >5 mm debris are in the 5-mm to 1-cm regime 5mm5 mm 1,000,000
Degradation threat 1 cm
ber to operational S/C mm
Nu 100,000
lative Main threat to 5 cm Main driver for uu operational S/C population growth
Cum 10,000 10 cm 50 cm 1 m
1,000 0.1 1 10 100 Size (cm)
69/72 JCL National Aeronautics and Space Administration Concluding Remarks (3/4)
• To address the root cause of the population growth (for large and small debris)
→ Target objects with the highest [ M × Pcoll ] – To maintain the future LEO debris population at a level similar to the current environment requires an ADR of ~5 massive intacts per year
• To address the main threat to operational satellites → Target objects in the 5-mm-to-1-cm regime – The small debris environment is highly dynamic and will require a long-term operation to achieve the objective
• Targeting anything else will NOT be the most effective means to remediate the environment nor to mitigate risks to operational satellites
70/72 JCL National Aeronautics and Space Administration Concluding Remarks (4/4)
• There is a need for a top-level, long-term strategic plan for environment remediation – Define “what is acceptable” – Define the mission objectives – Establish a roadmap/timeframe to move forward • The community must commit the necessary resources to support the development of low-cost andibld viable removal lth technol ogi es – Encourage dual-use technologies • Address non-technical issues, such as policy, coordination, ownership, legal, and liability at the national and i nt ernati onal lllevels
71/72 JCL National Aeronautics and Space Administration Preserving the Environment for Future Generations
• Four Essential “Cs” for ADR – Consensus – Cooperation – Collaboration – Contributions
Pre-1957 2011 2211
72/72 JCL